A waste toner collecting structure of an image forming apparatus includes a waste toner collector to be removably installed in a main body of an image forming apparatus to collect waste toner that is exhausted through exhaust holes of at least one waste toner exhaust parts installed in the main body a negative pressure generator to form negative pressure around shutters of the waste toner exhaust parts that open and close the exhaust holes, to form an intake air current into the waste toner collector and a waste toner separator to be connected to the waste toner collector to separate some of the waste toner, which flows into the waste toner collector and then moves toward the negative pressure generator, from air in order to collect the waste toner.